Discount chain Poundland is on the hunt for bigger stores after the cut-price chain, which sells everything from washing-up liquid to dogfood and pink cowgirl hats at a £1 a go, delivered a 130% leap in annual profits.

Chief executive Jim McCarthy revealed it was opening stores on retail parks – outlets which are 30% bigger than its typical outlets – as it reported pre-tax profits of £19.8m, up from £8.6m in the previous year. Sales jumped 28.7% to £509.8m in the year to 28 March as it filled the gap on the high street left by rival Woolworths. Like-for-like sales were up 0.7%.

McCarthy said its success was not due to penny-pinching in the recession, although an increasing number of AB shoppers seek out its eclectic wares, but "sustained growth… across the economic cycle". "In good times this is an excellent business," he said. "In bad times it is a robust business."

There is no confusion in Poundland's stores: it sells a range of 3,000 items, all for £1. The simplicity and strong value message has won fans up and down the country, with initial resistance in upmarket areas such as Twickenham quashed by the lure of boxes of Maltesers, reading glasses and Beauty Nation glam lashes. McCarthy said its stores in affluent areas such as Stratford upon Avon, Cambridge and Sutton Coldfield were also very successful. "I can understand that people might have reservations about a poundshop coming to their district," he said. "But you have to experience Poundland and it is very unusual for us to disappoint customers on the value we offer."

The rapid expansion of the West Midlands based business – it will open 50 stores this year – has made it harder for fast-moving-consumer-goods companies to ignore. One in three of the products it sells is a household brand, which was not the case when McCarthy took over in 2006, and the retailer now deals direct with businesses such as Heinz and Colgate. The discount market is expected to be worth £24.9bn by 2014.

"The growth of the discount market shows the consumer is chasing value and manufacturers are aware of that," said McCarthy. "They know we'll do their brands justice, sell big volumes and pay on time in full."

Poundland was sold by private equity firm Advent to rival buyout company Warburg Pincus in May, in a deal that delivered a £20m windfall for management. Nearly £5m of that went to McCarthy, who rather than cashing in the money made a substantial reinvestment in the business, taking a 20% stake. The former Sainsbury executive describes himself as "sad", saying: "I need to work but not because I need the money. I'm an insecure chap, like a lot of driven people. I love this business." His one extravagance has been taking his wife Rosemary on holiday to Tuscany.

With 293 stores Poundland has set a long-term target of opening 800 - the same number as Woolworths had when it collapsed. McCarthy said the chain had opened six retail park stores and is studying their performance, with initial analysis showing shoppers spending more.